1. Field of the Invention
This invention relates to solid state image sensing and display devices of the type used, for example, in high resolution electronic still cameras, electronic viewfinders and liquid crystal displays, and to the processing of signals in such devices.
2. Description of the Related Art
Referring first to FIG. 1, which is a schematic diagram illustrating a known interline type solid state image sensing device, there is provided an array of photoelectric conversion pixels 1 arranged in vertical columns and horizontal rows or lines. Vertical charge transfer units 2 are arranged in each column; and a horizontal charge transfer unit 3 is arranged below the columns. An output unit 4 is connected to receive charge outputs from the horizontal charge transfer unit 3 and to convert those charges to electrical signals which are output via an output terminal 5.
Signal charges are produced by the respective pixels 1 by means of photoelectric conversion. These charges are sent to the vertical charge transfer units 2 which, under the control of four-phase driving pulses xcfx86V1, xcfx86V2, xcfx86V3 and xcfx86V4, transfers them toward the horizontal charge transfer unit 3. Then the charge transfer unit 3, under the control of two-phase driving pulses xcfx86H1 and xcfx86H2, transfers these charges, on a line-by-line basis, to the output unit 4. The output unit 4 converts the charges to electrical signals which it outputs at the signal output terminal 5.
FIG. 2 is block diagram which illustrates a solid state image pickup apparatus. This apparatus includes an image sensing device 7 which is connected to be driven by a driving circuit 8. The image sensing device 7, converts light images to electrical charges by photoelectric conversion; and, in response to drive inputs from the driving circuit 8, transfers those charges to a signal processing circuit 9. The signal processing circuit 9 in turn is connected to supply processed signals to an image memory 12 which stores signals corresponding to the charges formed on each pixel of the image sensing device 7 in one frame of a sensed image. These stored image signals are then transferred from the memory 8 to an image display device 10. The image display device 10 also has pixels arranged in columns and rows or 2 lines; and these pixels convert the received electrical signals to light images.
The operations of the image sensing device driver 8, the signal processing device 9, the image memory 12 and the image display device 10 are coordinated by means of a synchronization device 11.
The image display device 10 has a smaller number of pixels in each vertical column than the number of pixels in the corresponding vertical columns of the image sensing device 7.
The display device 10 in a conventional solid-state image pickup apparatus, such as that shown in FIG. 2, may have a smaller number of pixels in its vertical columns than the number of pixels in the corresponding vertical columns of the image sensing device 7. In this case, the signal outputs of all the pixels of the image sensing device 7""s vertical columns are stored in the image memory 12; but when these signals are transferred to the image display device 10, they are supplied in such a manner that the signals corresponding to particular horizontal lines are omitted. This has the effect of reducing the number of pixels down to a value equal to the number of pixels in the image display device 10.
Such conventional solid state image pickup apparatuses, whose image display device has a smaller number of pixels in its 3 vertical columns than the number of pixels in the corresponding vertical columns of the associated image display device, the image sensing device always outputs a signal which includes all pixels in each image sensing operation. Since not all these pixels are used for the display, a longer than necessary amount of time is used in each image sensing operation. Furthermore, in cases where images are displayed sequentially, the next image cannot be updated in a sufficiently short time because of the long processing time required to write an image signal into the image memory and thereafter to read it out of the memory. This makes it difficult for a user to determine the composition of a picture.
Also, in order to reduce the number of pixels from the vertical rows of the stored image to that of the image display device, additional components, such as a special image memory and vertical signal reduction circuits are required. This causes an increase in the complexity of the circuits and an increase in production costs.
It is an object of the present invention to provide an improved method of, and apparatus for, reading pixel signals from a solid state image sensing device.
It is another object of the present invention to provide an improved method of, and apparatus for, reading pixel signals from a solid state image sensing device having a larger number of pixels in each vertical column; and applying the read signals to a display device having a smaller number of pixels in each vertical column.
It is still another object of the present invention to provide a method of, and apparatus for, reading an image signal from a solid state image sensing device so that the obtained signal has a high quality even when the image sensing device operates under darkened conditions.
According to one aspect of the invention, signals in an image pickup device having pixels arranged in vertical columns and horizontal lines are processed by reading signals from pixels in each of two lines in a group of n horizontal lines, where n is an integer equal to or greater than 3, adding together the signals of diagonally adjacent 2 k pixels, wherein k is an integer equal to or greater than 1, and also adding together the signals of vertically adjacent 2 k pixels.
According to another aspect of the invention, there is provided a novel image pickup apparatus having pixels arranged in vertical columns and horizontal lines. Control means are provided to read signals from pixels in each of two horizontal lines which are separated by at least two intermediate horizontal lines, then to add to each of a group of pixel signals read from one of the two horizontal lines with pixel signals that have been read from corresponding diagonally offset pixels in the other of the two horizontal lines, and to add each of a group of read pixel signals from the one horizontal line with signals that are read from corresponding, vertically adjacent, pixels in the other of the two horizontal lines.
According to a further aspect of the present invention there is provided a novel image pickup apparatus which comprises a solid state image sensing device having pixels arranged in vertical columns and horizontal lines, and an image display device which also has pixels arranged in vertical columns and horizontal lines, the number of pixels in the vertical columns of the image display device being less than the number of pixels in the vertical columns of the image sensing device. A control means is provided for controlling the image sensing device so that it outputs signals from pixels which are located in less than all of its horizontal lines. A signal processing circuit is also provided for applying the output signals from the image sensing device to the image display device.
These and other objects, features and advantages will become apparent from the following detailed description in conjunction with the accompanying drawings.